The use of irradiation process in stored grain may be the solution for the losses caused in these products by insects, as it does not induce resistance in the insects and leaves no toxic residue, and is considered an efficient and safe method of control of insects. The aim of the experiment was to determine the sterilizing dose of ionizing radiation from cobalt-60 to Alphitobius diaperinus (Panzer, 1797) (Coleoptera: Tenebrionidae) in peanuts irradiated in pupa stage. The experiment was conducted in the laboratory of Radiobiology and Environment of the Center for Nuclear Energy in Agriculture - CENA / USP., Piracicaba, SP, Brazil. Peanuts samples infested with pupae of A. diaperinus were utilized in the experiment that consisted of 8 treatments with 5 repetitions. Each repetition consisted of 20 pupae a total of 100 individuals per treatment. Were irradiated with doses of 0 (control), 25, 50, 75, 100, 125, 150 and 175 Gy, in a source of cobalt-60, Gammacell-220 type, with a rate dose of 381Gy / h. The experiment was conducted in a controlled temperature of 25 ?? 5 ?? C and relative humidity of 70 ?? 5%. After of irradiation process was evaluated of the number of emerged adult insects in each repetition in the treatments. The results showed that the sterilizing dose in F1 generation was 125 Gy and the pupa lethal dose 150 Gy. The dose of 150 Gy of gamma radiation can be used as phytosanitary treatment to control of immature stages of A. diaperinus infested peanuts.